The present invention relates a diffuser for a gas turbine engine, more particularly such a diffuser having an inlet with a generally circular configuration and an outlet having a non-circular configuration.
Diffusers in gas turbine engines are typically located between a compressor supplying compressed air or oxidizer and the combustion chamber. In engines having annular combustion chambers, the combustion chamber is bounded by inner and outer walls which are located within and spaced from inner and outer casings. Upstream ends of the inner and outer combustion chamber walls are interconnected by an upstream end wall and are further connected by a baffle which is spaced from the upstream end wall in a direction towards the diffuser.
Compressed air or oxidizer emanating from the compressor is directed into the diffuser which decelerates the air or oxidizer flow and may direct it onto the baffle which has openings to allow the air or oxidizer to pass through the baffle and through the air inlets in the upstream end wall of the combustion chamber into the combustion chamber. In known fashion, the air emanating from the diffuser may also be utilized to cool the inner and outer walls of the combustion chamber and to be directed through openings in the inner and outer walls into the primary combustion zone of the combustion chamber.
Gas turbine engines, such as turbojet aircraft engines, may utilize a single or double fuel injection head to inject fuel into the combustion chamber. In a single fuel injector head engine, a single annular array of fuel injectors inject fuel into the combustion chamber. In a double fuel injector head, two annular arrays are utilized to inject fuel into the combustion chamber, one fuel injector head being located radially outwardly of the other fuel injector head. As is well-known in the art, one of the fuel injector heads may be utilized to inject fuel during take-off conditions which require high output and the other fuel injector head may be utilized to inject fuel into the combustion chamber during idling or low-power operating conditions.
The diffuser decelerates the air or oxidizer emanating from the compressor so as to decrease the pressure drops in the air or oxidizer and to insure that it is fed properly to the combustion chamber. If the turbojet engine utilizes a double fuel injector head construction, the diffuser may include an annular flow splitter which enables the air or oxidizer emanating from the diffuser to be directed toward each of the fuel injector heads. Such a flow splitter enables the air or oxidizer to also be detoured over the baffle into the space between the inner and outer walls and the inner and outer casings, respectively for cooling the inner and outer combustion chamber walls, feeding the primary combustion zones and for dilution of the combustion gases.